Chromatically corrected objective with specifically structured and arranged dioptric optical elements and projection exposure apparatus including the same

摘要

An objective having a plurality of optical elements arranged to image a pattern from an object field to an image field at an image-side numerical aperture NA>0.8 with electromagnetic radiation from a wavelength band around a wavelength λ includes a number N of dioptric optical elements, each dioptric optical element i made from a transparent material having a normalized optical dispersion &Dgr;ni=ni(λ0)−ni(λ0+1 pm) for a wavelength variation of 1 pm from a wavelength λ0. The objective satisfies the relation  ∑ i = 1 N ⁢ &Dgr; ⁢ ⁢ n i ⁡ ( s i - d i )  λ 0 ⁢ NA 4 ≤ A for any ray of an axial ray bundle originating from a field point on an optical axis in the object field, where si is a geometrical path length of a ray in an ith dioptric optical element having axial thickness di and the sum extends on all dioptric optical elements of the objective. Where A=0.2 or below, spherochromatism is sufficiently corrected.